From the second edition (1989):
believe, v.
(bɪˈliːv) Forms: 2–3 bileuen, 4–5 bileue, -leve, -leeve, 4–6 beleue, -leve, 6–7 -leeve, 6– believe. (Also, 3 biliuen, byleuen, 4–5 byleeue, 4–6 byleue, -leve, 7 -leeue, -leive.) pa. tense and pple. believed, occas. in 6–7 beleft (still dial.). [Early ME. bileven, f. bi-, be- + leven:—OE., Anglian léfan, short. f. eléfan, WSax. elíefan, elýfan, a Common Teut. vb. (in OS. gilôƀian, Du. gelooven, OHG. gilouben, MHG. gelouben, glöuben, mod.G. glauben (earlier glouben, Gothic galaubjan):—OTeut. *galauƀian to believe, probably, ‘to hold estimable, valuable, pleasing, or satisfactory, to be satisfied with,’ f. galaub- ‘dear, pleasing’; cf. Goth. liuban, lauf, lubum, lubans, Teut. root *luƀ-, Aryan lubh-, to hold dear, to like, whence also love, lief. The original eléfan, ileven, ileve, survived to the 14th c., and the shortened leve to the 15th; the present compound, which eventually superseded both, appears in the 12th. The historical form is beleeve. Believe is an erroneous spelling of the 17th c., prob. after relieve (from Fr.). Cf. belief.]

I. intr.

1. To have confidence or faith in (a person), and consequently to rely upon, trust to. Const. in, and (in theological language) on (an obs.); formerly with into, unto, of (rare). On hine elýfan to believe in or on him, was common in OE. No difference can be detected between the use of ‘believe in’ and ‘believe on,’ in the 16th c. versions of the Scriptures, except that the latter was more frequent; it is now used chiefly (but not exclusively) of ‘saving faith.’ a. To believe in a person (also in Scripture in, or on, his name). [Cf. late L. credere in aliquem.]

c1200 Trin. Coll. Hom. 23 Ich bileue on þe holie gost. Ibid. 19 To bileuen in god. c1205 Lay. 13966 Woden ure lauerd, þe we on bi-liueð. 1340 Ayenb. 12 Ich beleue ine God. c1380 Wyclif Wicket (1828) 16 Into whome ye nowe not seynge bileue. 1382 —— John i. 12 To hem that bileueven in his name [so 1388, Geneva, Rhem; but Tind., Cranm., 1611 To them that beleeue on his name]. Ibid. viii. 30 Many men bileueden in to him [1388 in hym; Tind., Cranm., Geneva, 1611 on him; Rhem. in him]. Ibid. xiv. 1 Ȝe bileuen in to God, and bileue ȝe in to me [1388, Tind., Cranm., Geneva, Rhem., 1611 in God‥in me]. 1549 Bk. Com. Prayer Qvj, I Beleue in God the father almightie, maker of heauen and yearth. 1649 Bp. Reynolds Hosea iii. 7 All that should beleeve on him unto eternall life. 1860 Pusey Min. Proph. 279 To believe God is to believe what God says, to be true. To believe in or on God, expresses not belief only, but that belief resting in God, trusting itself and all its concerns with Him.

b. To believe in a thing, e.g. the truth of a statement or doctrine; also in mod. usage, in the genuineness, virtue, or efficacy of a principle, institution, or practice.

c1250 Lay. 13890 Ȝoure bi-leue Þat ȝeo an bi-lefeþ. 1569 J. Rogers Gl. Godly Love 181 We repent and beleeve in the promise of God in Christ. 1865 Mozley Mirac. vii. 139 In this sense St. Paul, if I may use the expression, believes in human nature; he thinks it capable of rising to great heights even in this life. a1887 Mod. To believe in universal suffrage, free education, vegetarianism, the college system; colloq. To believe in public schools, in the roast beef of Old England, in bicycles, the telephone, gas, etc. 1948 G. Vidal City & Pillar (1949) i. v. §2. 117 Sullivan believed in exercise.

c. Formerly with of = on, in.

c1532 Ld. Berners Huon (1883) 464 They were al content to leue theyr law and to byleue of Iesu chryst. 1630 E. Pagitt Christianogr. i. iii. (1636) 160 They do not well beleeve of the primacy of the Bishop of Rome.

d. absol. To exercise faith.

1377 Langl. P. Pl. B. v. 598 All þe wallis ben of witte‥Boterased with bileue-so-or-þow-beest-nouȝte-ysaved. 1562 J. Heywood Prov. & Epigr. (1867) 74 Beleue well, and haue well, men say. 1611 Bible Mark v. 36 Be not afraid, onely beleeue. 1627 Sanderson 12 Serm. (1637) 252 Who so forward as they to repent, and beleeue, and reforme their liues. 1633 Donne Poems (1650) 7, I can love‥Her who beleeves, and her who tries. 1870 M. Conway Earthw. Pilgr. xiv. 178 The man who really believes follows that which he believes, fearless of consequences.

e. absol. To think. Cf. 7.

1749 Fielding Tom Jones ii. vii. (1840) 160/2, I will not believe so meanly of you.

2. To give credence to (a person, or his statement); to trust (from L. credere alicui). Obs. Replaced by 5, 6.

1382 Wyclif 1 John iv. 1 Nyl ȝee bileue to eche spirit. —— John x. 37 If I do not the workis of my fadir nyle ȝe bileue to me [so 1388; Tindale and later versions, believe me not]. c1430 Life St. Kath. xviii. (Gibbs MS.) 71 At þe lest byleueth to ȝoure owne goddes [diis saltem vestris credite]. 1530 Love Bonavent. Mirr. (W. de W.) iii, Mary through mekenes byleuynge to the aungell Gabryell. 1647 W. Browne Polexander i. 67 Beleeve lesse to your courage then judgement.

3. ellipt. To believe in (a person or thing), i.e. in its actual existence or occurrence.

1716 Lady M. W. Montague Lett. ix. I. 29, I find that I have‥a strong disposition to believe in miracles. 1877 Sparrow Serm. xxii. 290 No civilized‥nation appears‥which did not believe in a God. Mod. To believe in ghosts, in the sea-serpent, in Romulus and Remus.

4. To trust, expect, think to do (something). Obs. Cf. belief 5.

c1400 Destr. Troy xxvii. 10919 Priam was proude, & prestly beleuyt For to couer of care thurgh hir kyd helpe. c1550 Scot. Poems 16th C. II. 109 Beleuand for to bring vs to despair. 1560 Whitehorne Arte of Warre (1573) 107b, There shall never bee founde any good mason whiche will beleeve to bee able to make a faire image of a peece of Marbell ill hewed.

II. trans.

5. To give credence to (a person in making statements, etc.). Object orig. dat.: cf. 2. Phrases. I believe you, an expression of emphatic agreement; believe (you) me, phr. strengthening an assertion.

1393 Gower Conf. I. 13 But if Gregoire be beleved, As it is in the bokes write. c1450 Merlin 3 Sholde he be bileved of moche peple. 1590 Shakes. Com. Err. v. i. 306 You are now bound to beleeue him. 1611 Bible Ex. xix. 9 That the people may‥beleeue thee for euer. 1627 May Lucan viii. 20 And scarse is he Beleft, relating his owne misery. 1646 Crashaw Delights of Muses 130 The modest front of this small floore, Beleeve mee, Reader can say more Then many a braver Marble can. a1674 Clarendon Hist. Reb. I. i. 4 A man‥who deserves to be beleived. 1743 Fielding J. Wild iii. iii. 208 Believe me, Lad, the Tongue of a Viper is less hurtful than that of a Slanderer. 1790 Walpole Let. 11 Dec. (1944) XI. 158 Believe me it is not for my own sake that I desire this. 1820 Moore Irish Melodies 51 Believe me, if all those endearing young charms‥Were to change by to-morrow [etc.]. 1832 Dickens Let. 4 Feb. (1965) I. 3 Believe me Yours Truly Charles Dickens. 1834 —— Sk. Boz (1836) ser. i. I. 175 ‘Were you not a little surprised?’ ‘I b'lieve you!’ 1859 Tennyson Enid 1592, I do believe yourself against yourself. 1910 Kipling Rewards & Fairies 233 ‘The tides run something furious here.’ ‘I believe you,’ said the Archbishop. 1918 C. Sandburg Cornhuskers 30 Pike's Peak is a big old stone, believe me. 1926 S.P.E. Tract XXIV. 119 Believe me (sometimes expanded to ‘believe you me’)—take my word for it. 1943 ‘E. M. Delafield’ Late & Soon iv. 63 Believe you me, that's no hardship. Ibid. ix. 123 Believe you me, in all the years, and all the adventures I've deliberately sought out‥it's never been like this. 1951 L. MacNeice tr. Goethe's Faust ii. iv. p. 256 No, you shall win it, believe you me. It's you to-day are C. in C. 1967 ‘O. Mills’ Death enters Lists v. 47 Someone's making a good thing out of the contracts, believe you me.

6. a. To give credence to, to accept (a statement) as true [cf. L. credere aliquid]. Also in colloq. phrases strengthening an assertion, as believe it or not, would you believe it? (see will v.1 43), you'd better believe (see better a. 4b).

c1315 Shoreham 7 He that bilefeth hit nauȝt. 1340 Ayenb. 151 Huanne me belefþ‥al þet God made, zayþ, and hat. c1380 Wyclif Wicket (1828) 6 They make us beleue a false law. 1528 More Heresyes i. Wks. 133/1 Ye be so cyrcumspect that ye will nothing beleue without good sufficient & full profe. 1549 Bk. Com. Prayer, Athan. Cr., This is the Catholike faithe: whiche excepte a man beleue faithfully, he cannot be saued. 1627 May Lucan vi. 262 Aulus beleft These fained words of his. 1649 Bp. Reynolds Hosea ii. 71 Our faith to beleeve Gods promises. 1667 Milton P.L. x. 42 Believing lies Against his Maker. 1741 Watts Improv. Mind ii. iii. 264 Men cannot believe what they will. 1776 H. More Let. (1925) 33 Would you believe it? In the midst of all the pomps and vanities of this wicked town, I have taken it into my head to study like a dragon. 1855 H. Reed Lect. Eng. Hist. ii. 67 It is‥as irrational to believe too little, as to believe too much. 1860 Tyndall Glac. i. §24. 171 The Guide Chef evidently did not believe a word of it. 1860 Trollope Framley P. II. ii. 35 Now, would you believe it? I have used up three lifts of notepaper already. 1929 R. L. Ripley (title) Believe it or not! 1931 L. Steffens Autobiogr. iii. xxxvi. 617 But the only individual he ever exposed was Martin Lomasy, who, believe it or not, was one of the best men I met in Boston. 1968 Sunday Express 8 Dec. 8/1 Having died for a minute and a half I suppose I am one of those believe-it-or-not Ripley characters.

b. To accept (a thing) as authentic. Obs.

1721 Strype Eccl. Mem. II. i. xv. 118 That these pensions should presently be sent to the hands of the auditors‥with strait commandment to believe the same patents immediately.

7. With clause or equivalent inf. phrase: To hold it as true that…, to be of opinion, think.

1297 R. Glouc. 229 Þe heþene Englysse men‥Byleuede, þat in heuene Godes hii were bo. 1393 Gower Conf. I. 273 To make us full beleve That he was verray Goddes sone. 1513 Bradshaw St. Werburge (1848) 32 Who byleveth her chast. 1603 Shakes. Meas. for M. iii. ii. 27, I beleeue I know the cause. 1667 Milton P.L. i. 144 Our Conqu'ror whom I now Of force believe Almighty. 1719 De Foe Crusoe (1858) 312 He believed there were more wolves a coming. 1853 H. Rogers Ecl. Faith 326 He believes‥that ‘probability is the guide of life.’ 1862 H. Spencer First Princ. ii. iv. §52 (1875) 172 If men did not believe this in the strict sense of the word‥they still believed that they believed it. 1875 Jowett Plato (ed. 2) I. 151 Some one—Critias, I believe—went on to say.

8. To hold as true the existence of. Obs. (Now expressed by 3.)

1481 Caxton Reynard (Arb.) 119 Ther ben many thynges in the world whiche ben byleued though they were neuer seen. 1708 Swift Sentim. Ch. Eng. Man Wks. 1755 II. i. 57 Whoever professeth himself a member of the Church of England, ought to believe a God. 1732 Berkeley Alciphr. v. §2 Shall we believe a God?

III. to make believe: to pretend. Subst. make-believe: a pretence; see make.